The goal of this project is to implement adaptive optics (AO) approach to stimulated emission depletion (STED) microscopy (AO-STED) so that the wavefront of the STED beam can be adaptively maintain to ensure the super-high spatial resolution in tissues. With the assistance of AO we will also develop the super-resolution microscopy with improved spatial resolution in both axial and lateral directions (AO3D-STED). The goal of this application is to develop an enabling method that can achieve a diffraction-unlimited resolution efficiently in deep tissue imaging; efficiently here means to achieve super-high resolution with minimum light exposure to the specimen. The proposed mechanism will be built as an addition to an existing home-built STED confocal/two-photon laser scanning microscope. We aim to create a robust advanced microscope that can be practically and routinely used for imaging various types of tissues without compromised resolution. The successful completion of this project will facilitate the widespread applications of super-high resolution imaging in biomedical research. PUBLIC HEALTH RELEVANCE (provided by applicant): The proposed project, if successfully completed, leads to an advanced microscopy imaging system that will maintain sub-diffraction-limited spatial resolution in tissues with different optical properties, thickness nd maintaining conditions. This system will benefit the biomedical research field in which high resolution and live tissue imaging are needed. The successful completion of this research project will make the microscope widely accessible to biologists and medical researchers.